Ceramic coatings for arc prevention between plasma facing components

This paper summarizes the results of preliminary insulation tests performed on copper samples covered with a Al
2
O
3
(aluminum oxide, commonly called alumina) film, deposited using the Atmospheric Plasma Spray (APS) technique.The electrical insulation tests were conducted in a vacuum chamber in the presence of weakly ionized plasma, in order to simulate the operating conditions that are expected in the plasma edge region in the RFX-mod2 experiment, in particular in the region included between the first wall and the copper passive stabilization shell.A minimum thickness of alumina deposit is required in order to ensure the dielectric rigidity required by the conditions of use in RFX-mod2. From electromagnetic simulations, it is estimated that the dielectric thickness must be such as to withstand a voltage greater than 1.5 kV.The experiments were carried out by applying a potential difference, generated by a bank of capacitors, between the sample and a copper pin placed in front of the alumina covered surface. The results of the tests conducted show that an alumina thickness of about 0.1 mm is sufficient to guarantee electrical insulation, up to a voltage of about 2.5kV.